Device for magnetising a ferrite rod extending in a microwave circulator



3,491,313 IN A Jan. 20, 1970 G. BUCHTA DEVICE FOR MAGNETISING A FERRITE ROD EXTENDING MICROWAVE CIRCULATOR Filed NOV. 29, 1967 INVENTOR.

FERI'RITE GERHARD BUCHTA FEGZ PRIOR ART iMQ United States Patent 3,491,313 DEVICE FOR MAGNETISING A FERRITE ROD EXTENDING IN A MICROWAVE CIRCULATOR Gerhard Buchta, Hamburg, Germany, assignor, by mesne assignments, to US. Philips Corporation, New York, N.Y., a corporation of Delaware Filed Nov. 29, 1967, Ser. No. 686,581 Int. Cl. H03h /00 US. Cl. 33324.1 4 Claims ABSTRACT OF THE DISCLOSURE A waveguide device has a ferrite body positioned within the waveguide, and an external magnet. Conductive magnetic bodies extend through the wall of the Waveguide to reduce the air gap in the magnetic field.

This invention relates to a device for magnetising a ferrite rod extending in a microwave circulator in parallel with one side of the wall of the hollow waveguide or in the radial direction.

It is known to use ferrite rods in hollow waveguides and to magnetise these rods by means of magnetising devices arranged externally of the wall of the waveguide, which magnetising devices are either of the electromagnetic type or also utilise at least one permanent magnet.

An arrangement for a broadband adjustable circulator is further known from the German utility sample No. 1,923,472, in which the balancing arrangements are secared to the wall of the waveguide and for this purpose the wall of the waveguide is open.

The present invention relates to a magnetising device of the kind mentioned in the preamble and avoids the large reluctance gaps of known arrangements in that at least one wall of the waveguide, for the purpose of reducing the reluctance gap in the waveguide is open at the height of this reluctance gap and replaced by at least one body of good magnetic conductivity.

Furthermore, the two opposing walls of the waveguide may be open. Also, the two walls of the waveguide may be replaced by bodies of good magnetic and electric conductivity one of which carries the ferrite rod.

For an arrangement including a permanent magnet, according to the invention this magnet may extend through the short-circuit body as well as in part through the walls of the waveguide.

In order that the invention may be readily carried into efiect it will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawing, in which:

FIGURE 1 shows a microwave circulator having a series branch including a ferrite rod which extends in parallel with one side of the wall of the waveguide,

FIGURE 2 shows the known kind of magnetisation using permanent magnets, in which the walls of the waveguide remain intact;

FIGURE 3 shows a kind of magnetisation according to the invention using permanent magnets with apertures in the two walls of the waveguide, and

FIGURE 4 shows a kind of magnetisation according to the invention in another form.

FIGURE 1 shows a continuous waveguide 1 having a branch 2 secured to the one broad side thereof. At the central branch point there is located a ferrite body 3 which does not extend throughout the width of the waveguide and which is secured to a body 4 of good electric conductivity. This body is attached to a wall 5 of the waveguide. A body 7 of good electric conductivity is secured to the opposing wall 6 of the waveguide in the axial direction of the bodies 3 and 4.

FIGURE 2 shows the walls 5 and 6 of the waveguide together with the electrically conductive bodies 4, 7 and the ferrite rod 3. Two permanent magnet bodies 9 and 10 are secured to a short-circuit body 8. The permanent magnet bodies 9 and 10 and the electrically conductive bodies 4 and 7 are separated in known manner by high reluctance gaps 5' and 6' of the waveguide walls 5 and 6, which cause an increase of the reluctance of the gap with the result that, for the same magnetisation of the ferrite body 3, the permanent magnet bodies 9 and 10 must be made of a larger size than in the case where, according to the invention, the walls 5 and 6 are open at least in part, as will be described hereinafter with reference to FIGURE 3.

FIGURE 3 shows this partial opening whereby the bodies 4 and 7 extend through the walls of the waveguide so that there are no high reluctance gaps at these areas. To this end the bodies 4 and 7 must also have god magnetic conductivity.

Another embodiment is shown in FIGURE 4, in which the permanent magnet bodies 9 and 10 extend through the short-circuit body 8 and also penetrate in part into the walls 5 and 6 of the waveguide.

What is claimed is:

1. A waveguide device comprising an elongated waveguide, a ferrite body positioned within said waveguide, magnet means having first and second poles disposed within and projecting externally from opposite walls of said waveguide and aligned with said ferrite body, and first and second bodies of magnetic conductive material extending through the walls of said Waveguide and contacting said first and second poles respectively, one of said conducting bodies contacting said ferrite body.

2. A device as claimed in claim 1 further comprising a magnetic short circuit means coupled to said magnet means.

3. A device as claimed in claim 2 wherein said magnet means project into said magnetic short circuit means.

4. A device as claimed in claim 1 wherein said magnetically conductive bodies are electrically conductive.

References Cited UNITED STATES PATENTS 6/1961 Seidel et al. 3/1963 Dewhirst 33324.l

US. Cl. X.R. 3331.1 

